5 Whys template: Ask why five times. Prove the answer once.
A 5 Whys analysis follows a problem from its symptom back to the process failure that caused it, one “why” at a time. Download the worksheet as Excel, PowerPoint or print-ready PDF, or fill it in right here in your browser. Free, no sign-up, no email.
What is a 5 Whys analysis?
5 Whys is the simplest root cause analysis method there is: state the problem, ask why it happened, then ask why of each answer until the chain reaches a cause the organization can act on. Taiichi Ohno called it the basis of Toyota’s scientific approach, and it has travelled with lean and Six Sigma into every industry since. Five is a rule of thumb, not a rule: some chains need three questions, some seven. What makes an analysis good is not the count but four habits.
One problem, stated in facts
What is wrong with what, where it was seen, since when and how often — measured, not described. No cause in the statement yet.
Every answer is something seen
Each “why” is answered from an observation, a record or a measurement, not from what seems likely. “Probably” is not an answer.
It ends at a process, not a person
The root cause is a standard that failed or is missing. “Operator error” is where the questions start, not where they stop.
The fix is checked
A countermeasure removes the root cause, has an owner and a date, and the problem’s measure is compared before and after.
5 Whys is a questioning discipline, not an investigation. It organizes what the team already knows and forces it into a chain of cause and effect that can be read, checked and acted on. What it cannot do is produce knowledge the team does not have: when nobody has seen the cause, a “why” gets a guess for an answer.
How to do a 5 Whys analysis, step by step
Six steps, each ending with something a reviewer can check. The worksheet has a box for each; the notes below say what belongs in it and how to tell a fact from a guess.
- 1
State the problem
Write down what is wrong with what, in measurable terms: the object and the defect, where the problem was seen, when it started, how many parts or how often. Keep causes and opinions out of the statement; a problem described as “the operator skipped a step” already contains its answer.
Check: Object, defect, place, time and quantity are all in the statement; a stranger could recognize the problem from it.
- 2
Go and see
Bring together the people who saw the problem — the operator, the inspector, the maintenance technician — and look at the part, the machine and the records before the first why is asked. Answers come from what was observed, so the people who observed it must be in the room.
Check: Everyone answering has seen the problem, the parts or the data, not only heard about them.
- 3
Ask why, answer with evidence
Ask why the problem happened and write the answer as a fact: what was observed, measured or found in a record. Then ask why of that answer. Each answer must be the direct cause of the one above it, not a different problem that happened to be around.
Check: Next to every answer stands its evidence: a reading, a photo, a log entry, a part in hand. “Probably”, “maybe” and “not enough” mark a guess.
- 4
Read the chain backwards
Read the chain from the last answer up, joining the links with “therefore”. If a link does not follow, the answer is incomplete or the chain has jumped. Then ask of each cause: if it had not happened, would the problem have occurred? A link that fails either test is not a cause.
Check: Every link passes the “therefore” test and the “if removed” test.
- 5
Stop at a process
Stop when the answer names a process or a standard that failed, is missing or was not followed — something the organization can change. A person’s mistake is not a stopping point: ask why the process allowed it. Stop before the fifth why if a process is reached; go past it if not.
Check: The root cause describes a process or a standard, not a name or a department; a countermeasure can change it.
- 6
Fix it, then check the fix
Choose a countermeasure that removes the root cause, not one that patches a symptom higher up the chain. Give it an owner and a date. Once it is in place, compare the problem’s measure before and after; if the problem came back, the chain was wrong somewhere.
Check: Countermeasure, owner and due date are recorded; the before-and-after data are in the follow-up box.
The classic example
Taiichi Ohno’s own illustration, from his book on the Toyota Production System: a machine stopped.
Problem The machine stopped.
- Why did the machine stop?An overload tripped the fuse.fact
- Why was there an overload?The bearing was not lubricated enough.fact
- Why was it not lubricated enough?The lubrication pump was not pumping enough oil.fact
- Why was the pump not pumping enough?The pump shaft was worn and rattling.fact
- Why was the shaft worn?Metal scrap had got into the pump with the oil: there was no strainer on the intake.fact
Root cause: no strainer on the pump intake — a missing standard, not a worn part.
Countermeasure: fit a strainer and add it to the pump specification. Replacing the fuse or the pump shaft would have fixed the problem until it came back.
Download the 5 Whys template
Three formats, the same worksheet, plus an online version. Free for your own and your company’s use: rename it, add your logo, adapt the fields. No sign-up, no email.
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Excel worksheet
.xlsxOne sheet to fill in, print-ready for A4 and Letter, with drop-downs for the yes/no and status fields and a guide sheet with the six steps and their checks.
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PowerPoint slides
.pptxThe worksheet as 16:9 slides for a team meeting or a management review: the problem, the five whys, root cause and countermeasures, follow-up.
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PDF for printing
.pdfPrint it and fill it in by hand at the machine or on a whiteboard. Two page sizes.
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Online worksheet
in your browserNothing to install. The worksheet saves itself in your browser as you type; print it or save it as a PDF when the analysis is done.
The files are provided free of charge for use within your organization, including commercial use. They may be adapted; they may not be sold or offered for download elsewhere. No warranty: see the Terms of Use. Files updated .
Fill in a 5 Whys online
The same worksheet as a web form. It saves as you type — in your browser only; nothing is sent to us or to anyone else. When the analysis is done, print it or save it as a PDF, or copy it as text into an email, a ticket or the root-cause section of an 8D report.
- Autosaves in your browser; reopen the page and continue where you left off.
- Print or save as PDF from the browser, with every box sized to its content.
- Copy the whole worksheet as plain text for an email, a ticket or the D4 section of an 8D.
- No account, no upload, no tracking of what you type.
Where 5 Whys stops working
A 5 Whys is only as good as its answers. When the cause is hidden, they become guesses.
The method works when every answer can be seen: an empty bin, a missing strainer, a skipped step, a setting that was changed. It stops working when the cause is hidden — when only some parts fail, when the failure comes and goes, when ten people can look at the process and see nothing wrong. The team still has to answer the next why, so it answers with what seems likely, and the countermeasure fixes the guess. A case that Shainin’s engineers describe shows how that looks.
The same method on a hidden cause
A field failure on an automotive electrical component. The first three answers were facts anyone could see; the fourth was not.
Problem A component in the field stopped working.
- Why did it stop working?It was not receiving current.fact
- Why no current?The mating connectors were no longer fully engaged.fact
- Why were they not engaged?The locking arm that holds them together had broken off.fact
- Why did the arm break?“It was not strong enough.”guess
The countermeasures on the table: a stronger material, thicker walls, a larger radius — a redesign of a validated part, for a failure that hit about one arm in a hundred.
What the parts showed: a test fixture was cracking some locking arms during the electrical check, and the cracks grew in the field. A small change to the fixture ended the failures. The design was never the problem.
Asking why
From the symptom down, one answer at a time
- Start from the symptom
- Answer each why from what the team knows
- Stop at an answer that sounds complete
- Fix the last answer
Works when every answer can be seen. When one cannot, the chain ends in a guess, and the fix is a change nobody has proved necessary.
Asking what’s different
From the measured difference between bad and good parts back to its cause
- Start from the measurement that defines the problem
- Contrast the best and the worst parts
- Eliminate what cannot be the cause; converge on the one that is
- Prove it by switching the problem on and off
One dominant cause — the Red X® — found from the parts themselves and confirmed with evidence.
Five signs a 5 Whys is guessing
- An answer contains “probably”, “not strong enough” or “operator error”.
- Only some parts fail, and the chain does not explain why those parts and not the others.
- Two teams ran the analysis and arrived at two different root causes.
- The countermeasure is retraining, awareness or more inspection.
- The problem came back after the countermeasure.
If two of these apply, the next why needs evidence, not a better guess. That evidence is what Shainin’s Red X® experts produce: the dominant cause, found by contrasting the best and worst parts and proved with a confirmation test the team can repeat. Shainin’s engineers call it “5 Why for hidden causes”.
5 Whys vs. fishbone, 8D and the rest
5 Whys is one of several tools for getting from a problem to its cause. They differ in how much they structure the search — and in what they do with a cause nobody has seen.
| Method | Best for | How it reaches the cause | What it does not do |
|---|---|---|---|
| 5 Whys | Problems whose cause can be observed: a missing step, a broken standard, a one-off event | A chain of why-questions, answered from what the team knows | Find a cause nobody has seen; verify the answers |
| Fishbone (Ishikawa) diagram | Collecting every candidate cause by category — man, machine, material, method, measurement, environment — before narrowing down | Brainstorming; the diagram orders the candidates, then each is checked | Rank the candidates or test them |
| 8D report | Escaped defects a customer wants contained, explained and signed off | Its D4 asks for a verified root cause; teams usually reach for a 5 Whys or a fishbone to fill it | Say how to find the cause |
| A3 report | Telling an improvement project on one page, with the PDCA cycle | Its root-cause box is typically a 5 Whys | Verify the cause beyond the team’s own judgement |
| Red X® problem solving | Recurring technical problems where only some parts fail and the cause is hidden | Contrasts the best and worst parts, eliminates what cannot be the cause and proves the one that is | Replace the report: its results go into the 5 Whys, the 8D or the A3 |
Inside an 8D report the 5 Whys usually lives in D4, root cause — and D4 is where customers reject reports most often, because a chain of plausible answers is not a verified cause. The same chain sits behind the root-cause box of most A3 reports and CAPA records.
5 Whys FAQ
What is the 5 Whys method?
A root cause analysis technique: state a problem, ask why it happened, then ask why of each answer in turn until the chain reaches a process failure the organization can correct. Each answer must be a fact the team has observed, and each must be the direct cause of the one above it. The method comes from the Toyota Production System and is now used in lean, Six Sigma, 8D reports, A3 problem solving and incident investigations in every industry.
Who invented the 5 Whys?
It grew up inside Toyota. The habit of asking why repeatedly is attributed to Sakichi Toyoda, the founder of the Toyota group; Taiichi Ohno, the architect of the Toyota Production System, made it a working method and described it in his 1978 book, published in English in 1988 as “Toyota Production System: Beyond Large-Scale Production”. His example — a machine that stopped because a missing strainer let metal scrap wear out a pump shaft — is still the one most people learn.
Do you always need exactly five whys?
No. Five is a rule of thumb that is usually enough to get past the symptoms and reach a process. Stop earlier when the answer already names a process or a standard that can be changed; keep going while it still names a person, a part or an event. Stopping at the fifth why because it is the fifth is one of the commonest ways to end at a symptom.
How do you write the problem statement for a 5 Whys?
As a fact about an object and a defect, with place, time and quantity: “12 of 400 housings from line 3 had a cracked boss at final inspection on Tuesday”, not “cracked housings” and not “the operator damaged the housings”. A statement that contains a cause has already decided the answer; a statement without numbers cannot be checked after the countermeasure.
What counts as a root cause in a 5 Whys?
A process or a standard that failed, is missing or was not followed, and that the organization can change: a pump specification without a strainer, a changeover procedure without a check, a maintenance interval set too long. A person’s mistake is a symptom of the process that allowed it; a worn part is a symptom of whatever wore it. If the countermeasure would be “tell people to be more careful”, the chain has stopped too early.
Can a 5 Whys have more than one root cause?
Yes. A why often has two or more true answers — the bin was empty, and nobody noticed — and each branch should be followed to its own process failure. The worksheet keeps one chain for clarity; for several branches, run one worksheet per branch or draw the chains as a tree. A fishbone diagram is the usual way to collect the branches before choosing which to follow.
What is the difference between 5 Whys and a fishbone diagram?
A fishbone (Ishikawa) diagram collects every candidate cause by category — man, machine, material, method, measurement, environment — and lays them out for discussion. A 5 Whys follows one chain of cause and effect in depth. Teams often use them together: the fishbone to list candidates, the 5 Whys to drill into the most likely one. Neither method verifies anything by itself: both end with what the team believes, not with what has been proved.
Is 5 Whys enough for root cause analysis?
For problems whose cause can be observed, yes — it is fast, needs no training and leaves a readable record. For hidden causes it is not: critics inside and outside Toyota have pointed out that different people reach different causes for the same problem, that investigators cannot find what they do not already suspect, and that the fifth why is an arbitrary depth. When only some parts fail and nobody can see why, the honest answer to a why is “we have not found out yet” — and finding out takes evidence from the parts, not another question.
How do you verify a root cause?
By showing that the problem can be switched on and off: remove or control the cause and the defect disappears, restore it and the defect returns, on enough parts that the result is not chance. For a process failure that was observed directly — the strainer was missing — the verification is the countermeasure itself and the before-and-after data. For a cause that was inferred, a confirmation test is the only proof; a chain of five plausible answers is not.
Is this template free, and can we use it in our company?
Yes. The Excel, PowerPoint and PDF files and the online worksheet are free for use within your organization, including commercial use, and may be adapted — add your logo, rename the fields, translate them. They may not be sold or offered for download on other sites. If the fourth why has no honest answer, talk to a Shainin expert.
Sources: Taiichi Ohno, “Toyota Production System: Beyond Large-Scale Production”, Productivity Press, 1988; ASQ, “What are the five whys and five hows?”; A. J. Card, “The problem with ‘5 whys’”, BMJ Quality & Safety 26(8), 2017; Shainin, “Refining the art of asking why: how to get the right answers from 5 Whys” and “8 problem-solving methods compared”.
Stuck at the fourth why?
When the honest answer is a guess, Shainin’s Red X® experts work to find and prove the dominant cause from the parts themselves — so the chain ends in evidence.